Pope John Paul II has celebrated the 25th anniversary of his election as leader of the world's Roman Catholics Thursday, issuing a new document addressing, among other things, immoral conduct by clerics. With the spotlight on the pope's declining health, observers have been watching him closely, as he presides over the anniversary festivities.

On his 25th anniversary as Pope, John Paul II began the day by meeting church leaders in the Vatican and signing a major document on the role of bishops. The 83-year-old pontiff looked tired, and only read part of his speech, slurring his words and leaving the rest to an aide.

With difficulty he managed to give his blessing to those gathered.

During the meeting, the pope told the assembled churchmen that he shares the "anxieties, suffering, hopes and joys of their ministry." He handed the document, or post-synodal exhortation, to the cardinals who greeted him.

In the document, the pope said that bishops must act quickly, specifically when dealing with crimes that involve immoral conduct. In a clear reference to the sex scandal that has rocked the church in the United States, the pope said bishops must be firm and impartial, when the cases involve church ministers.

The pope's document also reaffirmed the rule of celibacy for priests of the Roman Catholic Church. He said that bishops must encourage priests to remain faithful to their calling.

The pontiff condemned religious fundamentalism, saying the September 11, 2001, attacks in the United States had created serious uncertainty and fear, both for human civilization and the peaceful coexistence of nations.

Pope John Paul II will preside over a special anniversary mass Thursday evening. It will take place at around the same time that the white smoke came out of the Vatican chimney 25 years ago, announcing that a new Pope had been chosen.

The election of Polish-born Karol Wojtyla came as a big surprise. No one had expected a foreign cardinal from Eastern Europe to become the leader of the Roman Catholic Church.

Today, Pope John Paul II is the fourth longest-serving pontiff in the history of the church. He has traveled the world, helping bring down communism, working to heal divisions between Christians and Jews, and strongly advocating peace in the world.

Cardinals, dignitaries and thousands of pilgrims from all over the world will be attending the mass in Saint Peter's Square. There is a festive atmosphere in the Vatican, coupled with sadness and concern over the pope's clearly declining health.